I know I said I’d talk about IPv6 DNS records in this post, but I realized that we’d have to cover a few basics first. So lets cover those first before moving on…

IPv6 in your OS

Latest releases of all major OSes currently support IPv6 out of the box.

For Linux

IPv6 support has been available for the 2.4.x kernel, but it is recommended you switch to the 2.6.x kernel to be IPv6-up-to-date(among other reasons). To test if your server support IPv6, simply run the following command:

test -f /proc/net/if_inet6 && echo "Running kernel is IPv6 ready"

If it displays the “Running kernel is IPv6 ready” message, your server is IPv6 ready.

For Windows

Support for IPv6 is built into the latest versions of Microsoft Windows, which include Windows 7, Windows Server 2008 R2, Windows Vista, Windows Server 2008, Windows Server 2003, Windows XP with Service Pack 2, Windows XP with Service Pack 1, Windows XP Embedded SP1, and Windows CE .NET.

IPv6 at your DC

Support for IPv6 may not necessarily require new hardware, as support can enabled via software/firmware upgrades, if the current hardware has enough storage and memory space to support the new IPv6 stack.

However various “IPv6 ready” devices are being marketed with “advanced” support. So contact your DC if you need to know more. But if they are selling you servers IPv6 addresses by 2012, I guess its safe to assume they have the necessary equipment in place 🙂

The IPv6 Address Space

IPv4 uses a 32-bit address space. These 32 bits of data are stored as binary numbers(1’s and 0’s), but to make them easier for us to understand, they are displayed as blocks of decimal numbers separated by a “.”. Hence the familiar 192.168.1.1 notation.

IPv6 uses 128-bits of data to represent an IP address. So if we were to use the same decimal notation, it would go up to 39 digits. To avoid lengthy notations, IPv6 will use a hexadecimal notation. i.e. a combination of numbers 0-9 and letters a-f(10-15).

This reduces the number of characters required to represent an IPv6 address down to 32. IPv4 address are broken into 4 blocks of 8bits each separated by a “.”, IPv6 uses 8 blocks of 16 bits each separated by a “:”. So an IPv6 address in this notation would look something like this:

5852:d721:6b39f:0e32:99e6:34bb2:7134:43ff

But leading zeros in each block are omitted, and whole blocks of zeros are represented by “::”. So the address above would be more correctly represented as:

5852:d721:6b39f:e32:99e6:34bb2:7134:43ff

The familiar 127.0.0.1 “localhost” in IPv4 is represented as:
0000:0000:0000:0000:0000:0000:0000:0001
which shorten downs to:
::1

In my next post, we’ll talk about IPv6 DNS records and how they’ll be setup on your servers.